Wireless signaling.



I R. A. FESSENDEN. WIRELESS SIGNALING. APPLICATION FILED OOT. 10,-1901.

960,631. v Patented June 7, 1910.

2 SHEETS-SHEET 1.

R. A. PESSBNDEN. WIRELESS SIGNALING. APPLICATION FILED 001210, 1907.

960,631 Paten te d June 7, 1910.

2 SHEETS-SHEET 2.

l i i i, I o e. e 9

REGINALD A. FESSENDEN, OF BNT ROCK, MASSACHUSETTS.

Specification of Letters Patent.

wInELnss sldnamno.

Patented June '7, 1010.

Application flied October 10, 1907. Serial No. 398,817.

My invention relates to Wireless s1 aling and more especially to meansfor t e prevention of interference.

In the accompanymg drawings forming a part of this specification Figures1 and 2- are diagrams ofcircuits' for sending. Figs. 3 and 4 arediagrams of modified arrangements of circuits for receiving. Figs. 5 and6 show respectively a central section and a side elevat1on of a form ofgenerator for generating the electroma netic waves. d escribed has forits The invention herein object the more eilicient production andreceipt of wireless signals, and the production of such signals withoutinterfering with other" stations, and the receipt of such sigthe spacesare sent and not the male without interference from other stations.

In 1, 11 is a high frequency alternoting ynamo, 12 a tunin inductance,13 an antenna which may be either of the loop type, in which case it ispreferably though not necessarily ungrounded, or of the verti-, cal typeas shown, being in this case preferably grounded as at 14. 15 is thefield of the lug frequency dynamo, 10 the source of current excitin thefield, and 17 a telegra h key, whic on being depressed to form a at ordash, opens the field circuit and stops the emission of the h1g1frequency waves. It will be seen that when the hey is in its normalposition waves are being sent out and when depressed waves are not sentout, consequently with this apparatus 'ots and dashes as in the usualmethod.

Fig. 2 shows an alternative method which 13 is the antennae, 18 thesecondary of a transformer, 19 the primary, 20 a capacity, 21 and 22inductances,23 a he short .circuiting the inductance 22, 24 t esecondary of a second transformer, 25 its primary, 26 -1 capacity, 27 aninductance 29 a compressed gas spark ap, 30 an adjustable resistance, 31a source 0 continuous current. With this apparatus, the couplings of thetransformers 18 19 and 24, 25, respectively,

are preferably diflerent, though not neces. sarily so. That is,preferably, the coupling in one of the transformers may be tight and theother loose; as for example,the coupling between 18 and 19 may be tightand that between 24 and '25 maybe loose, or vice versa. The waves aregenerated continuously but by depressing the key 23, the frequency ofthe waves is altered. Instead of using the spark gap 29, a highfrequency alternating current dynamo 33 may be used by throwing theswitch 32 as shown. The electrical constants of the circuit arepreferably so arranged that the frequency will be less than 100,000where it is desired to send over long distances, as applicant has discovered that the absorption over long distances is very much less forfrequencies of 100,000 and under, and that with trequencies of 50,000for example, there is comparatively little absorption up to distances of2,000 miles during. daylight, whereas with frequencies of 200,000 thereis almost a total absorption.

Applicants invention includesthe broad discovery that, contrary to thestatement by Fleming and Marconi at page 618in the formers work onelectric wave telegraphy, the absorption does "not increase with thewave 1en'gth,.but instead, it reaches a certain maximum varying with theconditions but roughly between 100,000 and 200,000, and then decreaseswith great rapidity as the Wave length is increased. Applicant thereforeuses wave lengths beyond the point of maximum-absorption and as a rulelower than 100,000 per second, though not so low as to prevent ethcientsignaling.

In Fig. 3, 34 is a receiving antenna grounded at '37 35, 36 are theprimary and secondary of a transformer, the secondary 36 being connectedto the demagnetizing coil 38. 39 isan adjustable capacity and 40 anaudible frequency. The iron Wire 41, haw

ing thus impressed upon i a succession of variations of magnetism of afrequency to form a musical note, traverses the poles of the annullingmagnet 38 and under normal conditions the magnetism is wiped ofi' so asto produce no effect in .the 0011 -51 and the telephone 52. But when thekey 17 in Fig.

, phone 62 when no si 1 is depressed, and the transmitted impulsesinterrupted, the portions of the wire upon which the musical note hasnot been wiped off travel through the poles of the magnet 51 and producea musical note in the telephone 52. In this way it will be seen that theinverted sending is corrected by an inverted receiving and dots anddashes come out as musical notes.

In Fig. 4, 34 is the receiving antenna grounded at 37, 35 and 36 are theprimary and secondary of a transformer, 39 a variable capacity, 40 aninductance, 53 a receiver, for example a liquid barretter or telluriumreceiver, 54 a tuning fork vibrator producing a musical note, throughthe primary 48 and secondary 49 in the divided circuit 55, 53, 56 and55, 57, 58, 56. 57 is a capacity and 58 an adjustable resistance. 60 and61 are secondaries of the transformer connected to the telephonereceiver 62. The resistance 58 and capacity 57 are so adjusted that acontinuous sound is produced in the teleals are being received, but whensignals 0 the strength produced by the proper sending station arereceivedthe two divided circuits become balanced and no sound is heardin the telephone 62. This accomplishes the same purpose as the devicpshown in Fig. 3, 2'. e. reinverting the $1 a s.

1g. 5 shows an alternator of the well 7 known Mordey type, but designedto give high frequencies and having two air gaps and armatures. In thisfigure 63 is a revolving field inductor disk which may have the samenumber of field teeth on both edges but preferably has 1/5 of one percent. more on one side than on the other, so as to make the frequenciesgenerated by the two armatures also diifer, say 1/5 of one per cent,from each other. 64, 65 are two armatures supported by frame 91carrying, on rods 88 and 85, dash pots 87 and 93 the bearings 66 and 67so as to be always concentric with the shaft 68. 69 is a field coil andthe position of the armature winding 92 is shown in dotted lines in Fig.6. 70 and 71 are capacities. The armature 65 is in series with the coil72 and the armature64 with the coil 73. These coils are grounded asshown at 75, and the other terminals of the armature are grounded on theframe of the machine which is grounded at 76. The two coils 72, 73 areat right angles to one another so as to exert no inductive efi'ect oneach other. 77 is a movable coil capable of being rotated on thedetially as described.

72, so changing the frequency while kee ing the intensity constant. Oneterminal 0 the coil 77 is grounded at 74 and the other is -=connectedthrough the tuning inductance 83 to the antennae 84. In this Way ondepressing the key 78, the frequency is changed.

Fig. 6 is a side view of the alternator shown in Fig. ,5, and shows thesprings 85, 86 and dash pots 87, 88 whereby the armature is supportedflexibly and yet concentrically on the shaft 68. -By the inventionherein disclosed no disturbance is produced by a sending station onother stations unless they are exactly on'the same tune to 1/5 of oneper cent. Also it is practically impossible to interfere with areceiving station operating by this method,and very diflicult to readmessages, since they are sent 1n.1nverted form.

Having thus described my invention, what I claim as new and desire'tosecure by Letters Patent, is the following:

1. In apparatus for transmission of electric energy, the combinationwith a generator of practically continuous impulses at the sendingstation and a device to modify vices by which the combine effects of thef locally generated and the received impulses normally annul each othersefi'ects, whereby when the sent impulses are modified in character, anindicating efi'ect is produced by interrupting said normal mutualannulment 2. Apparatus for wireless telegraphy comprising a generator ofcontinuous electric impulses at the sending station and a device formodifying them, a generator of continuous impulses at the receivingstation, and devices operated by the combined eflects of the 10-callyogenerated and the received impulses to pr uce a musical note onlywhen the impu ses are modified in character, substan- 3. Apparatus forwlreless signaling comprising a generator of ractica y contlnuousimpulses of inaudible requency at the sending station and a device toalter their normal character, a generator of practically continuousimpulses at the receivin station, and devices operated thereby to e seta normal suppression of eii'ect, but permittin an indication b thereceived waves w en the same are a tered in character, substantially asdescribed.

4. In apparatus for wireless telegraphy, includin a sending stationhaving a generator o sustained oscillations operatively connected to thesending antenna, and a key for controlling the emlssion of theelectromagnetic waves so produced, a receiver operatively connected to areceivin antenna, and devices to produce a musica note corresponding tothe signals sent from the sending station, but the pitch of the musicalnote being determined by the apparatus at the receiving station andbeing independent of the apparatus at thesending station.

5. Apparatus for wireless signaling comprising means for practicallycontinuous generation of electroma netic waves, means at the receivinstation or producing a continuous flow 0 impulses and means for normallyannulling. their tefiect by impulses received, except when the normalcharacter of the sent impulses. is altered, substantially as described.

, 6. Apparatus for wireless signaling comrising electric means at areceiving station or continuously (producing a musical sound, means atthe sen ing station to continuously generate impulses and means at thereceiving station whereby said impulses silence said locally producedsound,'except when the sent impulses are interrupted 'for signaling.

7. Apparatus for signaling comprising means at a sending station tocontinuously generate impulses, means at a receiving station tocontinuously generate impulses and means by which the sent impulsesnormally annul their efiects, whereby a signal is made by altering thenormal character of the sent impulses.

In testimony whereof, I have hereunder signed my name in the presence ofthe two subscribed witnesses.

REGINALD A. FESSENDEN.

Witnesses:

Jnssm E. BENT, Annnumu WOLEVER.

